ACI 318-11 requires that the shotcrete walls on salt water pool be increased in strength and thickness. Shotcrete is defined as either the wet or dry process of pneumatically placing concrete.
ACI - The American Concrete Institute
ACI is the definitive expert on concrete. So much so, that they publish a myriad of standards that relate to concrete and it's use.
ACI Standard 318-11, "Building Code Requirements for Structural Concrete" has been directly incorporated into the International Building Code (adopted by 48 States, except Minnesota) and by the California Building Code. This effectively makes it the law of the land.
ACI 318-11 changes the requirements
ACI 318-11 redefined the parameters of the required coverage of concrete required over the reinforcing steel. Prior versions of ACI 318 were ambiguous as to what was actually defined as sulfate or corrosive conditions.
ACI 318-11 establishes the additional shotcrete protection required when exposed to defined levels of sulfates, water containing chlorides (salts) and permeability.
ACI 318-11, Table 4.2.1 indicates that shotcrete swimming pools are required to meet the criteria for Permeability - P1 (condition defined as: "in contact with water where low permeability is required") AND Corrosion Resistance - C2 ( a condition defined as: "concrete exposed to moisture and an external source of chlorides from
deicing chemicals, salt, brackish water, seawater, or spray from these sources").
The resulting P1 and C2 classifications require specific mix design ratios (ACI 318-11, Table 4.3.1).
ACI 318-11, Table 4.3.1, P1 classification sets a maximum water to cement ratio (w/cm2) of 0.50 and a MINIMUM 28 day compressive strength (f'c) of 4,000 PSI. While the C2 classification establishes a maximum water to cement ratio (w/cm2) of 0.40 and a MINIMUM 28 day compressive strength (f'c) of 5,000 PSI.
Therefore, any swimming pool that is going to be treated with sodium compounds is REQUIRED to have a maximum water to cement ratio (w/cm2) of 0.40 and a designed compressive strength (f'c) of 5,000 PSI. Sodium compounds utilized in swimming pool sanitization include sodium chloride (chlorine), sodium bromide (bromine) or sodium (salt-electrolysis chlorination).
The C2 classification (Table 4.3.1) further specifies that the requirements of ACI 318-11, 7.7.6 "Corrosive Environments" be met. Section 7.7.6 states that the coverage over reinforcing steel shall not be less than 2 inches for walls and slabs subject to such corrosive environments.
Structural Engineers & Building Departments
Many structural engineers and building departments do not abide by the requirements of ACI 318-11. They either attempt to justify design criteria less than the standards, are not versed on the most up to date requirements or simply fail to comply with the codes.
When there is an issue of structural integrity on your pool, the most recently adopted version of the IBC, CBC or ACI standards will apply in court, whether or not they were enforced by the engineer or building inspector.
Do you want to be left hanging with a structural engineer who will have to defend his decision to design a structure that was below the requirements of the building codes?
Do you want to take the risk that he will be able to convince a jury of lay people that a weaker structure is acceptable?
I thought not!
Contact the author, Paolo Benedetti of Aquatic Technology Pool and Spa at:
info@aquatictechnology.com or 408-776-8220.
Visit his website at: www.aquatictechnology.com.
All Contents © Aquatic Technology Pool & Spa, 2013.
All rights reserved.
Showing posts with label CBC. Show all posts
Showing posts with label CBC. Show all posts
Sunday, November 24, 2013
Monday, September 2, 2013
Concrete Filling Drilled Caissons - Don't just let the concrete fall
Filling drilled caissons with concrete - do not just let the concrete fall!
Free Fall
Recently, I was asked to weigh in on a project where the methods for placing concrete into drilled caissons were under debate.
The concrete contractor insisted that the concrete could be dropped from the surface down into the 40 foot hole. The swimming pool contractor did not feel comfortable with that, but did not know of any standards that dictated otherwise.
American Concrete Institute (ACI)
The ACI publishes a myriad of concrete standards. Most issues regarding concrete, are discussed in their standard ACI 318. ACI 318 has been adopted and incorporated into the International Building Code (IBC) as well as the California Building Code (CBC). The IBC is the basis for building codes relating to concrete, that have been adopted across the nation.
ACI 318 states that concrete should be placed as close to it's intended location as possible. So, in the case of drilled caissons, that means filling the hole from the bottom up. The weight of 40 feet of 3-4" concrete filled hose is unwielding. Usually a crane, backhoe or concrete boom is required to fill such deep holes.
California Building Code
The CBC is a little more compromising. It allows for the concrete to fall no more than 6 feet.
Separation
Why is there any concern at all? Separation.
If the concrete is allowed to fall a significant distance, the aggregate separates from the concrete. A homogenous mix is not delivered to the final resting place. Pumping the concrete from 40 feet also allows the concrete to bounce off of the reinforcing steel, also separating the aggregate from the cement.
To ensure that the specified mix design is delivered as specified, precise placement practices are critical.
Contact the author, Paolo Benedetti of Aquatic Technology Pool and Spa at: info@aquatictechnology.com or 408-776-8220.
Visit his website at: www.aquatictechnology.com.
All Contents © Aquatic Technology Pool & Spa, 2013.
All rights reserved.
Free Fall
Recently, I was asked to weigh in on a project where the methods for placing concrete into drilled caissons were under debate.
The concrete contractor insisted that the concrete could be dropped from the surface down into the 40 foot hole. The swimming pool contractor did not feel comfortable with that, but did not know of any standards that dictated otherwise.
American Concrete Institute (ACI)
The ACI publishes a myriad of concrete standards. Most issues regarding concrete, are discussed in their standard ACI 318. ACI 318 has been adopted and incorporated into the International Building Code (IBC) as well as the California Building Code (CBC). The IBC is the basis for building codes relating to concrete, that have been adopted across the nation.
ACI 318 states that concrete should be placed as close to it's intended location as possible. So, in the case of drilled caissons, that means filling the hole from the bottom up. The weight of 40 feet of 3-4" concrete filled hose is unwielding. Usually a crane, backhoe or concrete boom is required to fill such deep holes.
California Building Code
The CBC is a little more compromising. It allows for the concrete to fall no more than 6 feet.
Separation
Why is there any concern at all? Separation.
If the concrete is allowed to fall a significant distance, the aggregate separates from the concrete. A homogenous mix is not delivered to the final resting place. Pumping the concrete from 40 feet also allows the concrete to bounce off of the reinforcing steel, also separating the aggregate from the cement.
To ensure that the specified mix design is delivered as specified, precise placement practices are critical.
Contact the author, Paolo Benedetti of Aquatic Technology Pool and Spa at: info@aquatictechnology.com or 408-776-8220.
Visit his website at: www.aquatictechnology.com.
All Contents © Aquatic Technology Pool & Spa, 2013.
All rights reserved.
Subscribe to:
Posts (Atom)